Hi,

I've finished remaking and tidying my '91 2.0i Saphire pinto engine loom, car runs fine and smooth, everything is working, except for the car killing the voltage regulator. (I've changed it 3 times already, alternator is fine, something with the wiring is not).





Maybe I've messed up something with the exciter wire. It runs from battery + to instrument cluster charge indicator lamp, from there to alternator W+. Do I need to put any additional resistors or diodes between the indicator lamp and W+ terminal?

Any other thoughts on the problem? Voltage is fine, 14,2V for like 5 miles, then regulator dies. I've already tried other alternators, every single one does the same, problem is elsewhere. I have no idea, tried everything I could imagine.

 

That looks fine id check for a good alt earth to engine and engine to chassis and battery.

 

Thanks man, that's what others tell me also, but I've checked those earth cables several times. I'm going to reconnect those cables and try again but it's sad that as long as the issue is present I'm going to keep on wrecking regulators since there's no other way to test.

 

Check all earths using a multimeter in the ohms setting optimum is 0 ohms but 0.1 0.2 will be fine.

Run a good size earth from alt mounting 13mm long bolt to chassis and try.

Also what ampre wire are you using to battery.? It should be rated higher than the alt.

 

no you dont need a diode just need to wire it up properly [w] is not the warning light connection it is the phase tap u will find your battery goes flat out up a picture of the back of your alty u should have b + d+ w; b+ goes directly to the battery d+ goes to the warning light and w is sometimes used for rev counter take off [otherwise known as choke take off

 

Post up a pic of the rear connections of alternator.

What type u using ?

 

Yeah, sorry, mistyped, I used, and thought about D+, dunno why typed W+ (that isn't connected at all)

Just made measurements, highest reading was 0.1R, that should be OK I guess.
I haven't made direct ground from alt. to chassis, only engine-chassis. Should I do that?
My wires are fine, cleaned, tested every one of them.
I have this one:
Alternator (Not the one on the box)
Front side
Sorry about blurriness, I was lazy to go down the garage and make an actual photograph so used google.

 

M8 stud is your battery feed
M5/M6 stud is the warning light which would be the thin blue wiring to your clocks.

Check resistance from alt body mounting to battery neg terminal.

What is the lower terminal marking?

Regards
Paul

 

costina you are dead right on the wiring the post with the brown inulator will have w embossed into it

 

Diesels usually have that connected i guess. I try to stay away from oil burners lol

hope he sorts it. Nothing worse than electrical issues.

 

Thank you guys, I've tried everything, alternator charges, but way not enough. Voltage drops with load, thing is over my head.
I'll probably have to wait until January and take the alternator and/or the car to a professional.
Merry Christmas!

 

Unfortunately I'm back. Things haven't got any better, I've had the alternator completely rebuilt by a professional (lots of $$$).
Had my wires and connections checked (then checked again), earth cables, + wires, D+, everything.
Voltage regulator still breaks after some miles.

The only thing I haven't replaced is the battery. Is there ANY chance that a bad battery causes serial voltage regulator failures?

 

battery short could do this

 

I'm going to replace the battery (or borrow a working one) since that's my last option (although very unlikely). If battery proves to be ok, I'll have run out of any potential solutions and will probably burn the automobile to ashes.

 

This is very true a shit battery will fry the diodes a treat.